function greet() {
    console.log("hello there")
}

//函数表达式形式定义 speak 函数
const speak = function() {
    console.log("good day!")
}

//箭头函数 函数的一种简化写法
const hello = () => {
    console.log("hello")
}

//运行函数，函数名后面紧跟一堆括号
greet() //hello there
greet() //hello there

speak() //good day!
speak() //good day!

hello() //hello

greet() //hello there

function greet() {
    console.log("hello there")
}